This invention is an improvement over U.S. Pat. No. 4,023,889, also assigned to Morgan Adhesives Company, and particularly is designed to improve upon the process thereof in achieving a better support for the spacer layer so that no stretching or deformation of the spacer layer occurs during the lamination procedure. In addition, the process eliminates the use of a seal coat and combines bead coating and lamination into one step rather than in two.
There has been a great amount of patent and commercial activity on various procedures to make laminates and the compositions thereof in the retroreflective laminate field. Typical prior art patents include U.S. Pat. Nos. 2,432,928; 2,440,584; 2,543,800; 2,397,702 and 2,354,049 on various types of retroreflective laminates, including a layer of glass beads therein and their methods of production as have been developed heretofore. In addition, of course, the prior art cited in the above-identified application would be pertinent to this process.
It is the general object of the present invention to provide a retroreflective laminate having uniform physical properties therethrough, which laminate has excellent resistance to weathering and has good bonding between all layers in the laminate, and to provide a method for producing an improved retroreflective laminate in which the glass beads are securely positioned.
Another object of the invention is to provide a laminate which utilizes a supported spacer layer so that no stretching of the spacer layer occurs during its laminated application. The characteristics of the support are to utilize a paper film carrier which has a compressibility uniformity over its entire surface which is achieved by a paper carrier having relatively more and shorter fibers, providing a higher bulk density to the carrier film.
A further object of the invention is to eliminate the seal coating taught in the above-identified U.S. Pat. No. 4,023,889, as well as to provide bead coating and lamination in a single step rather than in two steps as taught by the previous invention.
The aforesaid and other objects of the invention which will become apparent as the detailed description proceeds are achieved by providing a method for forming a retroreflective laminate comprising a top coat layer, a binder layer, a spacer layer, optical beads in the binder layer, and a metal film adhered to the spacer layer which is characterized by
(a) forming the spacer layer on a paper carrier with release, said carrier having a compressibility uniformly over its entire surface and minimum stretch and deformation characteristics, PA1 (b) laminating the spacer layer together with the paper carrier to the binder layer with estranged beads, PA1 (c) removing the paper carrier, and PA1 (d) applying a metal film to the spacer layer.